Brian S Posner - Net Worth and Insider Trading

Brian S Posner Net Worth

The estimated net worth of Brian S Posner is at least $3 Million dollars as of 2026-09-10. Brian S Posner is the Director of Biogen Inc and owns about 7,400 shares of Biogen Inc (BIIB) stock worth over $2 Million. Brian S Posner is the Director of Bioverativ Inc and owns about 6,693 shares of Bioverativ Inc (BIVV) stock worth over $702,631. Brian S Posner is also the Director of Dyne Therapeutics Inc and owns about 24,500 shares of Dyne Therapeutics Inc (DYN) stock worth over $470,033. Besides these, Brian S Posner also holds Arch Capital Group Ltd (ACGL) . Details can be seen in Brian S Posner's Latest Holdings Summary section.

Disclaimer: The insider information is derived from SEC filings. The estimated net worth is based on the final shares held after open market or private purchases and sales of common stock with a transaction code of "P" or "S" on Form 4, assuming that Brian S Posner has not made any transactions after 2026-06-08 and currently still holds the listed stock(s). Please note that this estimate may not reflect the actual net worth.

Transaction Summary of Brian S Posner

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Brian S Posner Insider Ownership Reports

Based on ownership reports from SEC filings, as the reporting owner, Brian S Posner owns 6 companies in total, including Biogen Inc (BIIB) , Arch Capital Group Ltd (ACGL) , and Bioverativ Inc (BIVV) among others .

Click here to see the complete history of Brian S Posner’s form 4 insider trades.

Insider Ownership Summary of Brian S Posner

Ticker Company Transaction Date Type of Owner
BIIB Biogen Inc 2021-06-04 director
ACGL Arch Capital Group Ltd 2026-06-03 director
BIVV Bioverativ Inc 2018-03-08 director
LIMIT LIMIT 2014-06-03 director
LIMIT LIMIT 2006-08-01 other: Pres. & CEO & CoCIO of SubAdvis
LIMIT LIMIT 2026-06-08 director

Brian S Posner Latest Holdings Summary

Brian S Posner currently owns a total of 4 stocks. Among these stocks, Brian S Posner owns 7,400 shares of Biogen Inc (BIIB) as of June 4, 2021, with a value of $2 Million and a weighting of 57.08%. Brian S Posner owns 6,693 shares of Bioverativ Inc (BIVV) as of August 9, 2017, with a value of $702,631 and a weighting of 25.72%. Brian S Posner also owns 24,500 shares of Dyne Therapeutics Inc (DYN) as of June 8, 2026, with a value of $470,033 and a weighting of 17.2%. The other 1 stocks Arch Capital Group Ltd (ACGL) have a combined weighting of 0% among all his current holdings.

Latest Holdings of Brian S Posner

Ticker Company Latest Transaction Date Shares Owned Current Price ($) Current Value ($)
BIIB Biogen Inc 2021-06-04 7,400 210.73 1,559,402
BIVV Bioverativ Inc 2017-08-09 6,693 104.98 702,631
DYN Dyne Therapeutics Inc 2026-06-08 24,500 19.19 470,033
ACGL Arch Capital Group Ltd 2026-06-03 0 96.12 0

Holding Weightings of Brian S Posner


Brian S Posner Form 4 Trading Tracker

According to the SEC Form 4 filings, Brian S Posner has made a total of 0 transactions in Biogen Inc (BIIB) over the past 5 years. The most-recent trade in Biogen Inc is the sale of 360 shares on June 4, 2021, which brought Brian S Posner around $98,701.

According to the SEC Form 4 filings, Brian S Posner has made a total of 0 transactions in Bioverativ Inc (BIVV) over the past 5 years. The most-recent trade in Bioverativ Inc is the acquisition of 1,000 shares on August 9, 2017, which cost Brian S Posner around $59,190.

According to the SEC Form 4 filings, Brian S Posner has made a total of 7 transactions in Dyne Therapeutics Inc (DYN) over the past 5 years, including 7 buys and 0 sells. The most-recent trade in Dyne Therapeutics Inc is the acquisition of 2,000 shares on June 8, 2026, which cost Brian S Posner around $33,880.

More details on Brian S Posner's insider transactions can be found in the Insider Trading History of Brian S Posner table.

Insider Trading History of Brian S Posner

* The information on this page (including Insider Trading Shares, Share Changes, Cost, etc.) is sourced exclusively from Form 4 filings and does not incorporate any data from 13F or 13D/G filings. As a result, it may differ from the values shown on the Guru page.

No transactions are available. GuruFocus only tracks and displays the purchase and sale of non-derivative security in open market or private transactions from SEC filings with the transaction code of P or S.
Total 0
  • 1
Only the transactions in Open Market or Private Sale at the market prices are included. Other transactions such as conversion of derivative security or exercise of options are not included. Insiders are limited to only officers and/or directors of the company.

Brian S Posner Trading Performance

GuruFocus tracks the stock performance after each of Brian S Posner's buying transactions within different timeframes. To be detailed, the average return of stocks after 3 months bought by Brian S Posner is 17.95%. GuruFocus also compares Brian S Posner's trading performance to market benchmark return within the same time period. The performance of stocks bought by Brian S Posner within 3 months outperforms 14 times out of 18 transactions in total compared to the return of S&P 500 within the same period.

You can select different timeframes to see how Brian S Posner's insider trading performs compared to the benchmark.

Please note GuruFocus will not track the insiders’ transaction performance if he/she does not have buying transactions.

Performance of Brian S Posner

Average Return

LIMIT
Average return per transaction

Outperforming Transactions

LIMIT
9 out of 9 outperforming transactions.
Each transaction is measured over a period and compared to .
1 Month 3 Months 6 Months 1 Year 2 Years 3 Years
Return(%) 12.77 LIMIT LIMIT LIMIT LIMIT LIMIT
Relative Return to S&P 500(%) 10.85 LIMIT LIMIT LIMIT LIMIT LIMIT

Get the full picture on these stocks
See GF Score, valuation, financials, and warning signs for every stock Brian S Posner owns.
View BIIB Analysis

Brian S Posner Ownership Network

Ownership Network List of Brian S Posner

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Ownership Network Relation of Brian S Posner

Insider Network Chart


Brian S Posner Owned Company Details

What does Biogen Inc do?

Who are the key executives at Biogen Inc?

Brian S Posner is the director of Biogen Inc. Other key executives at Biogen Inc include Head of Pharm Ops and Tech Nicole Murphy , Head of Development Priya Singhal , and Head of Global Product Strat. Rachid Izzar .

Biogen Inc (BIIB) Insider Trades Summary

Over the past 18 months, Brian S Posner made no insider transaction in Biogen Inc (BIIB). Other recent insider transactions involving Biogen Inc (BIIB) include a net sale of 7,731 shares made by Priya Singhal , a net sale of 2,223 shares made by Rachid Izzar , and a net purchase of 1,235 shares made by Caroline Dorsa .

In summary, during the past 3 months, insiders sold 1,186 shares of Biogen Inc (BIIB) in total and bought 0 shares, with a net sale of 1,186 shares. During the past 18 months, 11,140 shares of Biogen Inc (BIIB) were sold and 1,238 shares were bought by its insiders, resulting in a net sale of 9,902 shares.

Biogen Inc (BIIB)'s detailed insider trading history can be found in Insider Trading Tracker table.

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Biogen Inc Insider Transactions

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Brian S Posner Mailing Address

Above is the net worth, insider trading, and ownership report for Brian S Posner. Based on the public information released on the U.S. Securities and Exchange Commission (SEC) website, Brian S Posner's mailing address is: Cambridge Ma 02142.